Add clock_settime and clock_nanosleep.

Add the missing prototypes, fix the existing prototypes to use clockid_t
rather than int, fix clock_nanosleep's failure behavior, and add simple
tests.

Bug: 17644443
Bug: https://code.google.com/p/android/issues/detail?id=77372
Change-Id: I03fba369939403918abcabae9551a7123953d780
Signed-off-by: Haruki Hasegawa <h6a.h4i.0@gmail.com>
diff --git a/libc/arch-x86_64/syscalls/__clock_nanosleep.S b/libc/arch-x86_64/syscalls/__clock_nanosleep.S
new file mode 100644
index 0000000..37726c0
--- /dev/null
+++ b/libc/arch-x86_64/syscalls/__clock_nanosleep.S
@@ -0,0 +1,17 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <private/bionic_asm.h>
+
+ENTRY(__clock_nanosleep)
+    movq    %rcx, %r10
+    movl    $__NR_clock_nanosleep, %eax
+    syscall
+    cmpq    $-MAX_ERRNO, %rax
+    jb      1f
+    negl    %eax
+    movl    %eax, %edi
+    call    __set_errno_internal
+1:
+    ret
+END(__clock_nanosleep)
+.hidden __clock_nanosleep